Should Cost, Acceptability, Feasibility, and Sustainability Be Included in Intervention Study Design?

Is an Effective Intervention Worth Adopting If It Is Too Expensive, Difficult, or Unsustainable?

A research team evaluates an intervention and reports favorable outcomes. Participants improve, the comparison is methodologically defensible, and the results suggest that the intervention may be beneficial. Yet an organization considering adoption faces questions that the effectiveness analysis does not answer.

How much would implementation cost? Would intended users and providers accept the intervention? Could it be delivered with existing personnel and infrastructure? Would the organization be able to maintain it after initial funding or researcher support ends?

These considerations can determine whether favorable research findings lead to practical use. However, adding multiple implementation measures can increase study complexity, participant burden, and resource requirements. Researchers must decide which questions belong in the original study and which may be more appropriately addressed through subsequent research.

Include These Outcomes When They Are Necessary for Interpreting or Acting on the Findings

Integrating Cost, Acceptability, Feasibility, and Sustainability Into Intervention Research

Why Are Effectiveness Outcomes Sometimes Insufficient for Implementation Decisions?

Effectiveness research examines whether an intervention produces the intended outcomes under specified conditions. However, decision-makers may also need to understand whether the intervention can be introduced, delivered, and maintained within their organizations.

An intervention may produce substantial benefits while requiring specialized personnel, expensive equipment, or intensive support unavailable in routine practice.

Alternatively, an intervention may be inexpensive and easy to administer but produce little meaningful improvement.

Researchers should therefore distinguish evidence of effectiveness from evidence of implementation suitability.

When adoption decisions are central to the research purpose, measuring implementation outcomes alongside effectiveness may provide a more complete basis for interpretation.

How Are Cost, Acceptability, Feasibility, and Sustainability Different?

These constructs concern related but distinct aspects of implementation. Their definitions should be established before selecting instruments or collecting data.

A favorable result in one domain does not establish success in another. An intervention can be acceptable but infeasible, feasible but expensive, or initially successful without being sustained.

What Does Intervention Cost Include?

Intervention cost may include the resources required to develop, introduce, deliver, monitor, and maintain an intervention. The appropriate scope depends on the economic question and analytical perspective.

For example, a digital educational intervention may require software licensing, instructor training, technical support, equipment, and staff time.

Researchers should distinguish costs associated with ordinary intervention delivery from research-specific costs such as additional assessments or data collection undertaken solely for evaluation.

Combining these categories without explanation may overstate the resources required for routine implementation.

The decision about when cost and resource use should be measured should follow from the study's intended economic and implementation questions.

Is Measuring Intervention Cost the Same as Conducting an Economic Evaluation?

No. A cost description identifies and values resources associated with an intervention. A formal economic evaluation compares alternative courses of action in terms of both costs and consequences.

For example, reporting that a training program costs a specified amount per participant provides useful resource information but does not establish whether it represents good value relative to an alternative.

A cost-effectiveness analysis would require appropriate comparison of incremental costs and outcomes, with the relevant perspective, time horizon, and uncertainty addressed.

Researchers should distinguish a descriptive implementation cost study from a full economic evaluation.

When comparative economic evidence is important, planning economic evaluation prospectively may improve the availability and quality of the necessary data.

Whose Costs Should Be Considered?

Costs can fall on institutions, providers, participants, families, or other stakeholders.

An intervention that appears inexpensive to an institution may impose substantial travel, connectivity, time, or equipment costs on participants.

Conversely, a participant-friendly intervention may require additional staffing or infrastructure.

The appropriate perspective depends on the research question and the decisions being informed.

Researchers should consider whether participant costs should be assessed alongside institutional costs when those costs could materially affect adoption, access, or interpretation.

How Should Intervention Costs Be Measured?

Cost measurement should begin by identifying the resources consumed and the perspective from which costs are evaluated.

Depending on the intervention, data may come from staff time records, expenditure accounts, procurement information, service utilization records, or structured resource-use instruments.

Researchers should distinguish quantities of resources from their monetary valuation. For example, recording ten hours of instructor training is a resource-use measurement, while assigning an appropriate monetary value to that time produces a cost estimate.

Costing methods should be transparent about assumptions, price year, currency, and relevant allocation rules.

Where formal economic evaluation is intended, established guidance such as the CHEERS 2022 reporting standards can support transparent reporting. CHEERS is a reporting framework, not a substitute for choosing an appropriate economic method.

What Is Intervention Acceptability?

Acceptability concerns whether stakeholders regard an intervention as agreeable, satisfactory, or suitable based on their experiences or expectations.

It can involve participants, providers, administrators, or others affected by implementation.

For example, students may find a digital feedback intervention useful while instructors consider its administrative workload excessive.

Researchers should specify whose acceptability is being assessed and recognize that stakeholder perspectives may differ.

Acceptability should not be treated as equivalent to satisfaction with a single feature or as proof of intervention effectiveness.

Can Acceptability Change Over Time?

Yes. Stakeholders may form expectations before using an intervention, develop opinions during implementation, and revise those opinions after sustained experience.

An intervention may initially appear attractive because of its novelty but become less acceptable when participants encounter repeated demands.

Conversely, users may initially resist an unfamiliar procedure and later find it acceptable after receiving appropriate training.

Researchers should therefore distinguish anticipated acceptability from experienced acceptability and select assessment times appropriate to the research question.

The theoretical framework of acceptability developed by Sekhon and colleagues provides a multidimensional approach to understanding acceptability rather than reducing it to a single general satisfaction judgment.

How Can Acceptability Be Measured?

Acceptability may be assessed through validated questionnaires, interviews, observations, or other appropriate methods.

Weiner and colleagues developed the Acceptability of Intervention Measure as part of a set of brief implementation outcome measures.

However, the suitability of an instrument depends on the population, language, intervention, and intended interpretation.

Qualitative inquiry may help explain why stakeholders find particular features acceptable or unacceptable.

Researchers should avoid assuming that high response rates or continued use necessarily demonstrate acceptability, since participation may also reflect institutional requirements or limited alternatives.

What Does Feasibility Mean in Intervention Research?

Feasibility concerns whether an intervention or research procedure can be carried out successfully under specified conditions.

It may involve staffing, infrastructure, time, training, organizational workflows, participant access, or the capacity to deliver essential components.

For example, an instructional intervention may be feasible in a small class but difficult to implement across large courses without additional support.

Feasibility is context-dependent. An intervention feasible in a well-resourced institution may not be feasible in another setting.

Researchers should define the conditions under which feasibility is being evaluated rather than describing an intervention as universally feasible or infeasible.

How Is Feasibility Different From Acceptability?

Acceptability concerns stakeholder perceptions, while feasibility concerns whether implementation can be accomplished.

For example, instructors may welcome a digital assessment system but lack sufficient time to provide the required feedback.

Alternatively, an institution may have the resources to implement a program even though students consider its procedures inconvenient.

Researchers should measure these constructs separately when both are important.

Combining them into one general implementation score can obscure differences that matter for practical decisions.

What Is the Role of Pilot and Feasibility Studies?

Pilot and feasibility studies can help determine whether an intervention and its evaluation procedures are workable before a larger effectiveness study.

They may examine recruitment, delivery, acceptability, resource requirements, retention, and the practicality of outcome measurement.

Bowen and colleagues describe several areas of focus for feasibility studies, including acceptability, demand, implementation, practicality, adaptation, integration, expansion, and limited-efficacy testing.

However, feasibility studies should not automatically be interpreted as definitive evidence of effectiveness.

Researchers should identify progression criteria that reflect the uncertainties the feasibility work is intended to resolve.

What Is Intervention Sustainability?

Sustainability concerns the continued delivery, integration, or maintenance of an intervention or its intended functions over time.

It becomes particularly important when an intervention is expected to continue after research funding, specialist support, or initial implementation efforts end.

For example, a university may successfully implement a digital tutoring program during a funded project but discontinue it when dedicated personnel are no longer available.

Sustainability should not be confused with the persistence of an intervention's effects among participants. A program may stop operating while some benefits remain, or it may continue operating without producing meaningful benefits.

These are distinct scientific questions.

When Can Sustainability Be Measured?

Direct evidence of sustainability generally requires observation over a period relevant to continued implementation.

A short trial may assess organizational readiness, anticipated resource commitments, or stakeholder intentions, but these are not equivalent to demonstrated long-term maintenance.

Researchers should specify the time horizon and what continued implementation means for the intervention.

For example, maintenance might be defined as continued delivery across subsequent academic terms, with essential intervention functions preserved.

Where long-term follow-up is not feasible, the study should describe its findings as preliminary indicators or determinants of sustainability rather than established sustainability outcomes.

Does Sustainability Require an Intervention to Remain Unchanged?

Not necessarily. Interventions may need adaptation as organizational conditions, technology, or user needs change.

The relevant question is whether essential functions and intended benefits can be maintained through appropriate changes.

However, substantial modification may produce a different intervention and require renewed evaluation.

Researchers should document adaptations and determine whether they preserve the components believed to be responsible for the intended effects.

The distinction between core and adaptable intervention components is therefore important when evaluating long-term implementation.

How Do Organizational Context and Resources Affect These Outcomes?

Cost, acceptability, feasibility, and sustainability may depend on organizational characteristics such as leadership, staffing, infrastructure, policies, and competing priorities.

For example, an intervention requiring extensive digital infrastructure may be feasible in one institution but difficult to implement in another.

Similarly, provider workload may affect acceptability even when participants value the intervention.

Researchers should consider the role of implementation context in intervention outcomes rather than interpreting implementation measures as fixed properties of the intervention alone.

Should All Four Constructs Be Measured in Every Intervention Study?

No. The appropriate selection depends on the intervention's development stage and the research decisions being informed.

An early efficacy study may need limited feasibility information without a comprehensive sustainability evaluation.

A pragmatic effectiveness study intended to inform organizational adoption may require more substantial evidence about cost, feasibility, and acceptability.

A study examining long-term institutional maintenance may prioritize sustainability and resource requirements.

Researchers should select constructs according to explicit objectives rather than treating a broad implementation checklist as a mandatory measurement package.

How Should These Constructs Be Integrated Into the Research Design?

Integration should begin during protocol development rather than after effectiveness data have been collected.

Researchers should define each selected construct, specify the relevant stakeholders, identify appropriate instruments or data sources, and determine assessment timing.

For example, cost data may require prospective resource-use recording, acceptability may require participant or provider questionnaires, feasibility may involve operational records, and sustainability may require follow-up after initial implementation.

The analysis plan should identify whether these are primary, secondary, exploratory, or descriptive outcomes.

When implementation questions are substantial, researchers should consider whether a hybrid effectiveness-implementation design would provide an appropriate methodological structure.

Can Collecting These Outcomes Increase Participant Burden?

Yes. Additional questionnaires, interviews, cost diaries, and follow-up assessments may increase demands on participants, providers, and organizations.

For example, collecting detailed time-use information may support a cost analysis but require repeated reporting.

Researchers should determine whether existing records can provide suitable information and whether instruments can be administered at fewer scientifically meaningful time points.

The question of whether economic data collection increases participant burden should be considered when planning detailed resource-use measurement.

Adding implementation outcomes should improve the scientific contribution of the study rather than simply increase its complexity.

How Should Cost and Implementation Findings Be Interpreted Together?

Researchers should avoid treating cost, acceptability, feasibility, and sustainability as interchangeable indicators of overall implementation success.

An intervention may be inexpensive but unacceptable, feasible but costly, or initially acceptable without being sustained.

Each outcome should be interpreted according to its definition, measurement, and relevant stakeholders.

Where multiple criteria inform an adoption decision, researchers should explain how those criteria are being considered rather than combine them into an arbitrary score.

Formal economic evaluations and structured decision analyses may be useful for particular decisions, but their methods and assumptions should be specified.

What Should Researchers Report?

Reports should identify which constructs were measured, why they were selected, the relevant settings and stakeholders, and how each was operationalized.

For cost measures, researchers should describe resource categories, valuation methods, and relevant assumptions.

For acceptability and feasibility, reports should identify the respondents, instruments, timing, and contextual conditions.

For sustainability, reports should specify the observation period and distinguish actual continued delivery from anticipated maintenance.

Researchers should also acknowledge important limitations, including missing data, limited follow-up, organizational selection, and uncertainty about applying findings to other settings.

Evaluating the Practical Adoption of a Digital Academic Support Intervention

Suppose the intervention improves learning and is well accepted but requires more technical support than the institution can sustain. The effectiveness result would remain informative, while the implementation evidence would identify an important limitation for adoption.

Conversely, an inexpensive and feasible intervention that does not improve learning would not become educationally valuable merely because it is easy to deliver.

The example illustrates why implementation outcomes should complement rather than substitute for evidence of intervention effectiveness.

Common Misconceptions About Cost, Acceptability, Feasibility, and Sustainability

How to Decide Which Implementation Considerations Belong in Your Study

Identify the decisions that will follow from the research. If the study is intended to inform adoption, expansion, or continued delivery, determine what evidence decision-makers need beyond intervention effectiveness.

Then select appropriate constructs, measurement methods, and assessment times rather than collecting implementation information indiscriminately.

The final design should provide evidence proportionate to the decisions it is expected to support. Researchers should avoid making implementation claims that extend beyond the outcomes and time periods actually measured.

Check Whether Your Intervention Study Addresses Practical Implementation

Frequently Asked Questions About Intervention Cost and Implementation

Practical Implementation Evidence Matters When Research Is Intended to Inform Adoption

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